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Hepatitis B vaccine

This factsheet has been written for members of the public by the UK Teratology Information Service (UKTIS). UKTIS is a not-for-profit organisation funded by Public Health England on behalf of UK Health Departments. UKTIS has been providing scientific information to health care providers since 1983 on the effects that medicines, recreational drugs and chemicals may have on the developing baby during pregnancy.

What is hepatitis B?

Hepatitis B is a viral infection that affects the liver and can, in some people, lead to lasting liver damage and/or liver cancer. Hepatitis B is passed on through contact with the blood or body fluids of an infected person, often via sexual contact or sharing needles to inject drugs. Healthcare and laboratory workers may also be at risk of catching hepatitis B through contact at work.

If a pregnant woman acquires hepatitis B the virus can pass from the mother to the baby in the womb, or during or after birth. Up to one in every three babies infected in this way will develop serious or fatal liver disease. Some (but not all) studies have also linked hepatitis B infection in pregnancy to preterm birth and low birth weight in the baby.

Hepatitis B occurs most commonly in parts of East Asia, sub-Saharan Africa, the Amazon, parts of Eastern and Central Europe, the Middle East, and the Indian subcontinent. It is less common in the UK.

Should I be vaccinated against hepatitis B if I am pregnant?

Hepatitis B vaccines (Energix®, Fendrix®, HBvaxPRO®) are given to reduce the risk of a person catching hepatitis B. UK guidelines recommend that pregnant women are vaccinated against hepatitis B if they are at risk of catching the illness.

Do I need to do anything if I had a hepatitis B vaccination but didn’t realise I was pregnant at the time?

There are currently no known risks to the mother or her unborn baby from being vaccinated against hepatitis B during pregnancy.

It is, however, always a good idea to let your doctor know that you are pregnant if you have been vaccinated or are taking any medicines. You and your doctor can then decide together whether you still need the medicines that you are on and ensure that you are taking the lowest dose that works. Your doctor will also be able to assess whether you need any additional monitoring during your pregnancy.

Can being vaccinated against hepatitis B in pregnancy cause my baby to be born with birth defects?

A baby’s body and most internal organs are formed during the first 12 weeks of pregnancy. It is mainly during this time that some medicines are known to cause birth defects.

No large studies have investigated whether birth defects are more common in babies born to women vaccinated against hepatitis B in pregnancy. So far the only published scientific information is from individual reports of 34 babies born to women who received the hepatitis B vaccine in early pregnancy. None of these babies had birth defects. Large, well-designed studies of many more women vaccinated against hepatitis B in pregnancy are therefore required.

Can being vaccinated against hepatitis B in pregnancy cause miscarriage?

No large studies have investigated whether hepatitis B vaccination in pregnancy increases the likelihood of miscarriage. Individual reports of 48 pregnant women who were vaccinated against hepatitis B in pregnancy do not raise a concern that the vaccine causes miscarriage, but large studies designed to specifically investigate this are required before any conclusions can be drawn.

Can being vaccinated against hepatitis B in pregnancy cause stillbirth?

No large studies have investigated whether stillbirth is more common following hepatitis B vaccination in pregnancy. Case series that include 245 pregnant women who were vaccinated against hepatitis B in pregnancy do not suggest that stillbirth occurred more often than to women in the general population. However, large, high quality studies that are specifically designed to scientifically measure the occurrence of stillbirth following hepatitis B vaccination in pregnancy are required to accurately answer this question.

Can being vaccinated against hepatitis B in pregnancy cause preterm birth?

No large studies have investigated whether preterm birth is more common following exposure to hepatitis B vaccine in pregnancy. Case reports of 132 pregnant women who were vaccinated against hepatitis B in pregnancy do not indicate that they had a higher chance of having a preterm birth compared to women in the general population. Further research is required to confirm this finding.

Can being vaccinated against hepatitis B in pregnancy cause my baby to be small at birth (low birth weight)?

No large studies have investigated whether low birth weight in the baby is more common following exposure to hepatitis B vaccine in pregnancy. There are case reports of 15 babies exposed to hepatitis B vaccine in the womb, all of whom had a normal birth weight. However, large, high quality scientific studies that assess the rates of low infant birth weight following hepatitis B vaccination in pregnancy are required to accurately answer this question.

Can being vaccinated against hepatitis B in pregnancy cause learning and behavioural problems in the child?

A baby’s brain continues to develop right up until the end of pregnancy. It is therefore possible that taking certain medicines at any stage of pregnancy could have a lasting effect on a child’s learning or behaviour.

No large studies have investigated learning and behaviour in children who were exposed in the womb to hepatitis B vaccines. There are case reports of 24 children exposed to hepatitis B vaccine in the womb, all of whom were developing normally when they were assessed between the ages of 2 and 22 months. However, large studies of many aspects of learning and development in children exposed in the womb to hepatitis B vaccine are required to accurately answer this question.

Will my baby need extra monitoring during pregnancy?

As part of their routine antenatal care, most women will be offered scan and blood tests from around 11 weeks of pregnancy, and a further scan at around 20 weeks to look for birth defects in the baby. Being vaccinated against hepatitis B in pregnancy is not expected to cause problems that would require extra monitoring of your baby.

Are there any risks to my baby if the father has been vaccinated against hepatitis B?

No studies have specifically investigated whether hepatitis B vaccine used by the father can harm the baby through effects on the sperm, however most experts agree that this is very unlikely. More research on the effects of medicine use in men around the time of conception is needed.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org.

General information

Up to 1 out of every 5 pregnancies ends in a miscarriage, and 1 in 40 babies are born with a birth defect. These are referred to as the background population risks. They describe the chance of these events happening for any pregnancy before taking factors such as the mother’s health during pregnancy, her lifestyle, medicines she takes and the genetic make up of her and the baby’s father into account.

Medicines use in pregnancy

Most medicines used by the mother will cross the placenta and reach the baby. Sometimes this may have beneficial effects for the baby. There are, however, some medicines that can harm a baby’s normal development. How a medicine affects a baby may depend on the stage of pregnancy when the medicine is taken. If you are on regular medication you should discuss these effects with your doctor/health care team before becoming pregnant.

If a new medicine is suggested for you during pregnancy, please ensure the doctor or health care professional treating you is aware of your pregnancy.

When deciding whether or not to use a medicine in pregnancy you need to weigh up how the medicine might improve your and/or your unborn baby’s health against any possible problems that the drug may cause. Our bumps leaflets are written to provide you with a summary of what is known about use of a specific medicine in pregnancy so that you can decide together with your health care provider what is best for you and your baby.

Every pregnancy is unique. The decision to start, stop, continue or change a prescribed medicine before or during pregnancy should be made in consultation with your health care provider.It is very helpful if you can record all your medication taken in pregnancy in your hand held maternity records.

www.medicinesinpregnancy.org

Disclaimer: This information is not intended to replace the individual care and advice of your health care provider. New information is continually becoming available. Whilst every effort will be made to ensure that this information is accurate and up to date at the time of publication, we cannot cover every eventuality and the information providers cannot be held responsible for any adverse outcomes following decisions made on the basis of this information. We strongly advise that printouts should NOT be kept for any length of time, or for “future reference” as they can rapidly become out of date.